This seems to be General Reference, a quick Google search brings the answer up in several resources.
– NominSimOct 5 '12 at 15:55

2

Check Wikipedia for "Marauder's Map"; it automatically redirects here, where it says the twins stole it from Filch.
– IzkataOct 5 '12 at 15:55

2

@DVK "General Reference" doesn't mean it has to appear on the first page of hits. Regardless, if you append "Wikipedia" to your search it should be one of the top hits.
– NominSimOct 5 '12 at 16:06

1

@NominSim - Atwood's exact wording for GR was "...because these types of questions can be definitively and permanently answered by a single link to a standard internet reference site with no additional explanation necessary". Now compare a little blurb in a 200-page Wiki artice NOT exclusively devoted to marauder's map to an actual answer produced by Katey (which actually includes, like, a canon reference :)
– DVK-on-Ahch-ToOct 5 '12 at 16:30

4

link Reading that section answers the question. Unless we are expected to explain how to read I feel like that sufficiently qualifies for "general reference". I'll agree with "First page of Google hits" if you append "wikipedia" to your search, otherwise that criteria is pointless as Google customizes search results based on user's web history.
– NominSimOct 5 '12 at 16:35

1 Answer
1

George and Fred Weasley stole it from Argus Filch's storage cabinet of confiscated items when they'd been brought in by him for misbehaving. Filch presumably confiscated it from another student, but I don't know that it is ever confirmed from whom he confiscated the map.

From Harry Potter and the Prisoner of Azkaban:

“Well . . . when we were in our first year, Harry — young, carefree,
and innocent —”
Harry snorted. He doubted whether Fred and George had ever
been innocent.
“— well, more innocent than we are now — we got into a spot
of bother with Filch.”
“We let off a Dungbomb in the corridor and it upset him for
some reason —”
“So he hauled us off to his office and started threatening us with
the usual —”
“— detention —”
“— disembowelment —”
“— and we couldn’t help noticing a drawer in one of his filing
cabinets marked Confiscated and Highly Dangerous.”
“Don’t tell me —” said Harry, starting to grin.
“Well, what would you’ve done?” said Fred. “George caused a
diversion by dropping another Dungbomb, I whipped the drawer
open, and grabbed — this.”
“It’s not as bad as it sounds, you know,” said George. “We don’t
reckon Filch ever found out how to work it. He probably suspected
what it was, though, or he wouldn’t have confiscated it.